For power control at an interconnection node in a wind farm, conventionally, as disclosed in, for example, Patent Citations 1 and 2, it is suggested that a central controller transmit a uniform reactive power command to individual wind turbines so that the individual wind turbines control generators based on the reactive power command.
Patent Citation 1:    U.S. Pat. No. 7,166,928, specification
Patent Citation 2:    U.S. Pat. No. 7,224,081, specification